The present invention relates to an electro-mechanical interlock and module system for an electrical device, such as an electric lawn mower, that controls the operative state of the device.
In various types of power equipment, such as an electric lawn mower, it is desirable to preclude inadvertent or unauthorized operation of the power switch and hence of the equipment controlled thereby. The prior art has proposed various means for accomplishing this function, which typically comprise mechanisms that selectively present a mechanical interference to the operation of the power switch. However, the primary disadvantage of these interlock mechanisms is that they are not "user friendly". In other words, the inconvenience caused by such mechanisms is frequently a source of user complaint and can even lead to users devising ways of defeating the interlock feature altogether, thereby eliminating the safety benefits of the mechanism.
Accordingly, it is the primary object of the present invention to provide an interlock system for an electrically powered device, such as an electric lawn mower, that is "user friendly", and yet is effective to completely disable the device.
In addition, it is an object of the present invention to provide an interlock system that is particularly adapted for use with a cordless, rechargeable, electrically powered device, such that when the interlock system is in a first position the device is disabled and the charging system is operable, and in a second position the device is enabled and the charging system is inoperable.
Furthermore, it is an object of the present invention to provide an improved interlock and module system that is configured to provide ease of assembly and ensure proper alignment between interactive components of the system.
In general, the present invention, which in the preferred embodiment is incorporated into a cordless, rechargeable lawn mower, employs a mechanical "key" member that is adapted for insertion into a specially configured opening in the top of the motor shroud. The key member includes a cam surface that engages and actuates the plunger of a normally open interlock switch when the key member is fully inserted into the opening, thereby closing the switch and enabling the lawn mower power circuit. Simultaneously, an integral tab portion on the key member blocks the charging port so that the operator cannot connect the male plug from an outlet mounted charging transformer to the charger circuit when the power circuit is enabled. Conversely, when the key member is removed from the shroud, the normally open interlock switch returns to its OFF position and the power circuit of the lawn mower is disabled. In addition, with the key member removed, the charging port is exposed, thereby permitting connection of the charger circuit to a charging transformer.
Significantly, the power circuit of the lawn mower also includes a conventional handle-mounted ON/OFF switch that controls the application of power to the motor when the power circuit in enabled. However, when the power circuit is disabled by the interlock switch, power cannot be applied to the motor, regardless of the position of the handle-mounted ON/OFF switch. Thus, unauthorized operation of the lawn mower, by children for example, is prevented.
The preferred embodiment of the present invention also incorporates unique means for enhancing ease of assembly while at the same time ensuring proper alignment between the various interactive components of the interlock system. The configuration of the key member and the corresponding opening in the shroud are also designed to discourage the intentional insertion of foreign objects into the opening to defeat the purpose of the interlock system.
Additional objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiment which makes reference to the drawings of which: